Manufacture of n, n&#39;-dihydroanthraquinone-azine



United fitates Patent MANUFACTURE OF N,N'-DIHYDROANTHRA- QUINONE-AZINEHermann Thielert, Leverkusen-Wiesdorf, and Fritz Baurnann,Leverkusen-Bayerwerk, Germany, assignors to Farbenfahriken BayerAktiengesellschaft, Leverltusen, Germany, a corporation of Germany NoDrawing. Application August 18, 1953, Serial No. 375,045

Claims priority, application Germany August 27, 1952 4 Claims. (Cl.260263) This invention relates to the manufacture ofN.N'-dihydroanthraquinone-azine from a-aminoanthraquinone. In ourcopending application Ser. No. 256,118, filed November 13, 1951, we havedescribed a process for the production ofN.N'-dihydroanthraquinone-azine by melting 1 part by weight ofa-amino-anthraquinone with less than 4 parts by Weight of an alkaliphenolate in the presence of an oxidation agent, such as alkalichlorates, alkali nitrates and potassium persulfate and an alkali metalsalt of a lower fatty acid.

N.N-dihydroanthraquinone-azine can also be obtained froma-amino-anthraquinone in good yields by carrying out the above reactionin the presence of gases containing oxygen, for instance air, asoxidation agent. These gases containing oxygen are intimately contactedwith the reaction mixture, for instance by intensely stirring, and theprocess is preferably performed in the presence of catalysts, forinstance iron chloride, iron oxide, manganese dioxide, manganesesulfate, cobalt chloride and copper acetate. Also mixtures of thesecatalysts may be used.

The reaction is preferably carried out at temperatures between aboutl75225 C. It is of advantage to employ a gas with an oxygen content notbelow about 10% since otherwise the yield of the dyestuif is decreased.

The invention is further illustrated by the following examples withoutbeing restricted thereto, the parts being by weight:

Example 1 50 parts of potassium hydroxide (90%) are introduced into 75parts of molten phenol at 100 C. and then heated to 130 C. 20 parts ofsodium acetate are added at 140-160 C. and then 1.5 parts of manganesesulfate and 2 parts of copper acetate. At l95-200 C. 50 parts ofa-amino-anthaquinone are added to the melt With intensively stirring andintroducing air. The temperature is maintained for 3 /2 hours at 210 C.and then at 220 C. for 2 /2 hours. Thereupon the melt is poured into 2liters of Water, boiled for one hour and filtered with suction in theheat after addition of 5 cc. of a concentrated sodium bisulfitesolution. The filter cake is washed with hot water several times anddried.

The crude dyestuff is dissolved in 600 parts of concentrated sulfuricacid and the solution adjusted with water to an acid content of 83%.After filtering, washing and drying the dyestufi is obtained in pureform.

Other catalysts, for instance iron oxide, iron chloride and cobaltchloride may be used with equal success instead of manganese sulfate.Furthermore the air may be passed over the melt instead of into themelt.

Example 2 parts of potassium hydroxide (90%) are introduced into partsof molten phenol at about 100 C. 40 parts of anhydrous sodium acetateand then 4 parts of iron oxide or manganese dioxide are added at C. tothe potassium phenolate thus obtained. The melt is heated to ZOO-210 C.and 100 parts of tat-aminoanthraquinone are added while intensivelystirring and conducting air over the melt. Care has to be taken that thetemperature does not drop below 194 C. After 67 hours heating at210-220" C. the reaction is complete.

The dyestuff is purified as described in Example 1. Instead of air, amixture of air and oxygen may be used with the same good result.

We claim:

1. Process for the manufacture of N.N-dihydroanthraquinone-azine whichcomprises heating together 1 part by weight of a-aminoanthraquinone withless than 4 parts by weight of an alkali phenolate, an alkali salt of alower fatty acid, an inert gas containing at least about 10% free oxygenand a heavy metal catalyst of the group consisting of iron chloride,iron oxide, manganese dioxide, manganese sulfate, cobalt chloride andcopper acetate at temperatures of about -225 C.

2. Process for the manufacture of N.N'-dihydroanthraquinone-azine whichcomprises heating together 1 part by weight of a-aminoanthraquinone with2 parts by weight of an alkali phenolate, an alkali salt of a lowerfatty acid, an inert gas containing at least about 10% free oxygen and aheavy metal catalyst of the group consisting of iron chloride, ironoxide, manganese dioxide, manganese sulfate, cobalt chloride and copperacetate at temperatures of about 175-225 C.

3. Process for the manufacture of N.N-dihydroanthraquinone-azine whichcomprises heating together 1 part by weight of a-aminoanthraquinone with2 parts by weight of an alkali phenolate, alkali acetate, an inert gascontaining at least about 10% free oxygen and a heavy metal catalyst ofthe group consisting of iron chloride, iron oxide, manganese dioxide,manganese sulfate, colbalt chloride and copper acetate at temperaturesof about l75-250 C.

4. Process for the manufacture of N.N-dihydroanthraquinone-azine whichcomprises heating together 1 part by Weight of a-aminoanthraquinone with2 parts by weight of an alkali phenolate, an alkali salt of a lowerfatty acid, air, and a heavy metal catalyst of the group consisting ofiron chloride, iron oxide, manganese dioxide, manganese sulfate, cobaltchloride and copper acetate at temperatures of about 175-225 C.

No references cited.

1. PROCESS FOR THE MANUFACTURE OF N.N''-DIHYDROANTHRAQUINONE-AZINE WHICHCOMPRISES HEATING TOGETHER 1 PART BY WEIGHT OF A-AMINOANTHRAQUINONE WITHLESS THAN 4 PARTS BY WEIGHT OF AN ALKALI PHENOLATE, AN ALKALI SALT OF ALOWER FATTY ACID, AN INERT GAS CONTAINING AT LEAST ABOUT 10% FREE OXYGENAND A HEAVY METAL CATALYST OF THE GROUP CONSISTING OF IRON CHLORIDE,IRON OXIDE, MANGANESE DIOXIDE, MANGANESE SULFATE, COBALT CHLORIDE ANDCOPPER ACETATE AT TEMPERATURE OF ABOUT 185-225* C.